text: These databases are invaluable resources in the field of aquatic toxicology because the likelihood that a chemical will cause toxicity is highly variable across the broad spectrum of contaminants in the environment. This is because the likelihood of adverse effects on an organism is dependent on the concentration of that substance in the target tissues of the organism, the physicochemical properties of that chemical and the duration of exposure to the chemical. Tools capable of predicting the toxicity of specific chemicals to particular organisms or groups of organisms are essential to regulators and researchers in the field of toxicology.